Isolated cleft palate is the commonest craniofacial birth anomaly (e.g., 4.5 per 10,000 births in the US). It creates problems in feeding, speech, hearing, and dental development. Unsuccessful surgery may fail to resolve these problems and reduce the child's potential for social development and inclusion. At this time there is an inadequate evidence base for selecting the optimal timing for surgery. There is however a plausible case for undertaking surgery at 6 months, rather than the more usual timing of 12 months, as the provision of a functioning palate when speech skills begin to develop may lead to better speech outcomes. A randomized control trial will be undertaken to compare the outcomes of surgery performed either at age 6 months or at age 12 months. All infants will receive the same type of palate surgery. Approximately 650 infants will be enrolled and followed until age 5 years. The key inclusion variables are that they have non-syndromic cleft palate, they have been independently judged to be medically fit for surgery, and their parents consent to participation. The main outcome will be insufficient velopharyngeal function assessed by blinded judges. Secondary outcomes will be surgical complications, articulation, hearing, and dentofacial development. Recruitment will take 3 years. The findings will be applicable to children with cleft palate in any part of the world. The clinical sites will be members of an international consortium of cleft centers who recently completed enrollment of 925 infants into large scale trials of unilateral cleft lip and palate sponsored by the European Commission and NIDCR: the Scandcleft Network (10 surgical sites serving all of Denmark, Finland, Norway and Sweden and five regional centers in the UK); and a large specialized cleft center in Brazil (USP-HRAC, Bauru). Project Narrative: Improving the evidence base for cleft palate surgery will improve the treatment and social integration of affected children, reduce the burden of remedial care that they and their families must endure, and reduce the cost of care associated with cleft palate.